Use standard Spring utils in MongoDB module

This commit replaces usages of custom assert utility class with standard one from Spring Framework, and removes the custom utility.

See gh-2170

spring-session-data-mongodb/src/integration-test/java/org/springframework/session/data/mongo/integration/AbstractClassLoaderTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018 the original author or authors.
+ * Copyright 2014-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,7 +26,6 @@ import org.springframework.context.ApplicationContext;
 import org.springframework.core.serializer.DefaultDeserializer;
 import org.springframework.core.serializer.support.DeserializingConverter;
 import org.springframework.session.data.mongo.AbstractMongoSessionConverter;
-import org.springframework.session.data.mongo.Assert;
 import org.springframework.session.data.mongo.JdkMongoSessionConverter;
 import org.springframework.util.ReflectionUtils;
 
@@ -49,8 +48,7 @@ public abstract class AbstractClassLoaderTest<T> extends AbstractITest {
 
 		Field mongoSessionConverterField = ReflectionUtils.findField(this.sessionRepository.getClass(),
 				"mongoSessionConverter");
-		ReflectionUtils.makeAccessible(
-				Assert.requireNonNull(mongoSessionConverterField, "mongoSessionConverter must not be null!"));
+		ReflectionUtils.makeAccessible(mongoSessionConverterField);
 		AbstractMongoSessionConverter sessionConverter = (AbstractMongoSessionConverter) ReflectionUtils
 				.getField(mongoSessionConverterField, this.sessionRepository);
 
@@ -70,7 +68,7 @@ public abstract class AbstractClassLoaderTest<T> extends AbstractITest {
 	private static Object extractField(Class<?> clazz, String fieldName, Object obj) {
 
 		Field field = ReflectionUtils.findField(clazz, fieldName);
-		ReflectionUtils.makeAccessible(Assert.requireNonNull(field, fieldName + " must not be null!"));
+		ReflectionUtils.makeAccessible(field);
 		return ReflectionUtils.getField(field, obj);
 	}
 

spring-session-data-mongodb/src/main/java/org/springframework/session/data/mongo/AbstractMongoSessionConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2016 the original author or authors.
+ * Copyright 2014-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -36,6 +36,7 @@ import org.springframework.session.DelegatingIndexResolver;
 import org.springframework.session.FindByIndexNameSessionRepository;
 import org.springframework.session.IndexResolver;
 import org.springframework.session.PrincipalNameIndexResolver;
+import org.springframework.util.Assert;
 
 /**
  * Base class for serializing and deserializing session objects. To create custom
@@ -123,7 +124,8 @@ public abstract class AbstractMongoSessionConverter implements GenericConverter
 	protected abstract MongoSession convert(Document sessionWrapper);
 
 	public void setIndexResolver(IndexResolver<MongoSession> indexResolver) {
-		this.indexResolver = Assert.requireNonNull(indexResolver, "indexResolver must not be null!");
+		Assert.notNull(indexResolver, "indexResolver must not be null");
+		this.indexResolver = indexResolver;
 	}
 
 }

spring-session-data-mongodb/src/main/java/org/springframework/session/data/mongo/Assert.java

@@ -1,40 +0,0 @@
-/*
- * Copyright 2019 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.springframework.session.data.mongo;
-
-import org.springframework.lang.Nullable;
-
-/**
- * Utility to verify non null fields.
- *
- * @author Greg Turnquist
- */
-public final class Assert {
-
-	private Assert() {
-	}
-
-	public static <T> T requireNonNull(@Nullable T item, String message) {
-
-		if (item == null) {
-			throw new IllegalArgumentException(message);
-		}
-
-		return item;
-	}
-
-}

spring-session-data-mongodb/src/main/java/org/springframework/session/data/mongo/MongoIndexedSessionRepository.java

@@ -22,6 +22,7 @@ import java.util.Map;
 import java.util.Optional;
 import java.util.stream.Collectors;
 
+import com.mongodb.DBObject;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.bson.Document;
@@ -38,6 +39,7 @@ import org.springframework.session.MapSession;
 import org.springframework.session.events.SessionCreatedEvent;
 import org.springframework.session.events.SessionDeletedEvent;
 import org.springframework.session.events.SessionExpiredEvent;
+import org.springframework.util.Assert;
 
 /**
  * Session repository implementation which stores sessions in Mongo. Uses
@@ -97,9 +99,9 @@ public class MongoIndexedSessionRepository
 
 	@Override
 	public void save(MongoSession session) {
-		this.mongoOperations
-				.save(Assert.requireNonNull(MongoSessionUtils.convertToDBObject(this.mongoSessionConverter, session),
-						"convertToDBObject must not null!"), this.collectionName);
+		DBObject dbObject = MongoSessionUtils.convertToDBObject(this.mongoSessionConverter, session);
+		Assert.notNull(dbObject, "dbObject must not be null");
+		this.mongoOperations.save(dbObject, this.collectionName);
 	}
 
 	@Override